Semiconductor devices and methods of manufacturing the same

ABSTRACT

Methods of forming an integrated circuit device are provided. The methods may include forming a gate structure on a substrate, forming a first etch mask on a sidewall of the gate structure, anisotropically etching the substrate using the gate structure and the first etch mask as an etch mask to form a preliminary recess in the substrate, forming a sacrificial layer in the preliminary recess, forming a second etch mask on the first etch mask, etching the sacrificial layer and the substrate beneath the sacrificial layer using the gate structure and the first and second etch masks as an etch mask to form a source/drain recess in the substrate, and forming a source/drain in the source/drain recess. A sidewall of the source/drain recess may be recessed toward the gate structure relative to an outer surface of the second etch mask.

CROSS-REFERENCE TO RELATED APPLICATION

This U.S. non-provisional patent application claims priority under 35U.S.C. §119 to Korean Patent Application No. 10-2015-0079348, filed onJun. 4, 2015, in the Korean Intellectual Property Office, the disclosureof which is hereby incorporated by reference in its entirety.

BACKGROUND

The inventive concepts relate to a semiconductor device and a method ofmanufacturing the same. More particularly, the inventive concepts relateto a semiconductor device including a fin field effect transistor and amethod of manufacturing the same.

A semiconductor device may include an integrated circuit includingmetal-oxide-semiconductor field effect transistors (MOSFETs). As sizesand design rules of semiconductor devices have been reduced, sizes ofMOSFETs have also been scaled down. Performances of semiconductordevices may be deteriorated by the scale down of the MOSFETs. Thus,various researches are being conducted to improve performances of highdensity semiconductor devices.

SUMMARY

A method of forming an integrated circuit device may include forming agate structure on a substrate, forming a first etch mask on a sidewallof the gate structure, anisotropically etching the substrate using thegate structure and the first etch mask as an etch mask to form apreliminary recess in the substrate, forming a sacrificial layer in thepreliminary recess, forming a second etch mask on the first etch mask,etching the sacrificial layer and the substrate beneath the sacrificiallayer using the gate structure and the first and second etch masks as anetch mask to form a source/drain recess in the substrate, and forming asource/drain in the source/drain recess. The first etch mask may bebetween the sidewall of the gate structure and the second etch mask. Asidewall of the source/drain recess may be recessed toward the gatestructure relative to an outer surface of the second etch mask.

In various embodiments, etching the sacrificial layer and the substratemay include exposing a sidewall of the preliminary recess.

According to various embodiments, forming the first etch mask mayinclude forming the first etch mask having a thickness of about 1 nm toabout 10 nm on the sidewall of the gate structure such that a sidewallof the preliminary recess is spaced apart from the sidewall of the gatestructure by about 1 nm to about 10 nm.

In various embodiments, an upper portion of a sidewall of thepreliminary recess may be substantially perpendicular to a lowermostsurface of the gate structure.

In various embodiments, the preliminary recess may be a firstpreliminary recess, and etching the sacrificial layer and the substratemay include etching the sacrificial layer and the substrate using thegate structure and the first and second etch masks as an etch mask toform a second preliminary recess in the sacrificial layer and thesubstrate and removing the sacrificial layer to form the source/drainrecess in the substrate.

According to various embodiments, the second preliminary recess mayextend through the sacrificial layer.

According to various embodiments, etching the sacrificial layer and thesubstrate may include performing an anisotropic etch process and anisotropic etch process.

In various embodiments, etching the sacrificial layer and the substratemay etch the sacrificial layer faster than the substrate.

A method of forming an integrated circuit device may include forming agate structure on a substrate, forming a sacrificial layer adjacent asidewall of the gate structure in the substrate, forming an etch mask onthe sidewall of the gate structure and a portion of the sacrificiallayer, etching the sacrificial layer and the substrate beneath thesacrificial layer using the gate structure and the etch mask as an etchmask to form a source/drain recess in the substrate and forming asource/drain in the source/drain recess. An upper portion of a sidewallof the sacrificial layer may be substantially perpendicular to alowermost surface of the gate structure.

According to various embodiments, an uppermost sidewall of thesource/drain may be recessed toward the gate structure relative to anouter surface of the etch mask.

According to various embodiments, the uppermost sidewall of thesource/drain may be substantially perpendicular to the lowermost surfaceof the gate structure.

In various embodiments, etching the sacrificial layer and the substratemay include etching the sacrificial layer and the substrate using thegate structure and the etch mask as an etch mask to form a preliminaryrecess that extends through the sacrificial layer and removing thesacrificial layer to form the source/drain recess in the substrate.

According to various embodiments, removing the sacrificial layer mayinclude exposing a sidewall of the preliminary recess such that thesidewall of the preliminary recess may be a portion of a sidewall of thesource/drain recess.

According to various embodiments, forming the sacrificial layer mayinclude etching the substrate to form a recess adjacent the sidewall ofthe gate structure in the substrate and performing an epitaxial growthprocess using a surface of the recess as a seed layer to form thesacrificial layer in the recess. The sidewall of the recess may besubstantially perpendicular to the lowermost surface of the gatestructure.

A method of forming an integrated circuit device may include forming agate structure on a substrate and forming a first recess adjacent asidewall of the gate structure in the substrate. A sidewall of the firstrecess may be substantially perpendicular to a lowermost surface of thegate structure and may be spaced apart from the sidewall of the gatestructure by a first distance. The method may also include forming asacrificial layer in the first recess, forming a second recess thatextends through the sacrificial layer and in a portion of the substratebeneath the sacrificial layer, removing the sacrificial layer to form asource/drain recess in the substrate and forming a source/drain in thesource/drain recess. An uppermost sidewall of the second recess beingspaced apart from the sidewall of the gate structure by a seconddistance that is greater than the first distance.

In various embodiments, the second recess may have a depth greater thana depth of the first recess.

According to various embodiments, removing the sacrificial layer mayinclude exposing the sidewall of the first recess such that the sidewallof the first recess may be a portion of a sidewall of the source/drainrecess.

In various embodiments, the first distance may be about 1 nm to about 10nm.

According to various embodiments, the uppermost sidewall of the secondrecess may expose the sacrificial layer.

According to various embodiments, an uppermost sidewall of thesource/drain may be spaced apart from the sidewall of the gate structureby a third distance that is smaller than the second distance.

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive concepts will become more apparent in view of the attacheddrawings and accompanying detailed description.

FIG. 1A is a perspective view illustrating a semiconductor deviceaccording to some embodiments of the inventive concepts.

FIG. 1B is a cross-sectional view taken along the lines I-I′, II-II′,and III-III′ of FIG. 1A.

FIGS. 1C and 1D are cross-sectional views taken along the line IV-IV′ ofFIG. 1A.

FIGS. 2A and 2B are enlarged views of the portions ‘A’ and ‘B’ of FIG.1B, respectively.

FIG. 3 are cross-sectional views taken along the lines I-I′, III-III′and IV-IV of FIG. 1A to illustrate a semiconductor device according tosome embodiments of the inventive concepts.

FIGS. 4A, 5A, 6A, 7A, 8A, 9A, 10A and 11A are perspective viewsillustrating a method of manufacturing a semiconductor device accordingto some embodiments of the inventive concepts.

FIGS. 4B, 5B, 6B, 7B, 8B, 9B, 10B and 11B are cross-sectional viewstaken along the lines I-I′, II-II′ and III-III′ of FIGS. 4A to 11A,respectively.

FIG. 7C is a cross-sectional view taken along the lines I-I′, II-II′,and III-III′ of FIG. 7A.

FIG. 9C is an enlarged view of the portion ‘A’ of FIG. 9B.

FIG. 9D is cross-sectional views taken along the lines I-I′, II-II′ andIII-III′ of FIG. 9A.

FIG. 12A is a cross-sectional view taken along the lines I-I′, II-II′and III-III′ of FIG. 1A to illustrate a semiconductor device accordingto some embodiments of the inventive concepts.

FIG. 12B is a cross-sectional view taken along the line IV-IV′ of FIG.1A.

FIG. 13 is a cross-sectional view taken along the lines I-I′, III-III′and IV-IV′ of FIG. 1A to illustrate a semiconductor device according tosome embodiments of the inventive concepts.

FIGS. 14 to 21 are cross-sectional views taken along the lines I-I′,II-II′ and III-III′ of FIG. 1A to illustrate a method of manufacturing asemiconductor device according to some embodiments of the inventiveconcepts.

FIG. 22 is a circuit diagram of a complementarymetal-oxide-semiconductor static random access memory cell (CMOS SRAMcell) including a field effect transistor according to exampleembodiments of the inventive concepts.

FIG. 23 is a block diagram illustrating an electronic system including asemiconductor device according to some embodiments of the inventiveconcepts.

FIG. 24 is a block diagram illustrating an electronic device including asemiconductor device according to some embodiments of the inventiveconcepts.

FIG. 25 illustrates a mobile phone implemented with an electronic systemaccording to embodiments of the inventive concepts.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The inventive concepts will now be described more fully hereinafter withreference to the accompanying drawings, in which example embodiments ofthe inventive concepts are shown. The advantages and features of theinventive concepts and methods of achieving them will be apparent fromthe following example embodiments that will be described in more detailwith reference to the accompanying drawings. It should be noted,however, that the inventive concepts are not limited to the followingexample embodiments, and may be implemented in various forms. Theexample embodiments are provided so that this disclosure will bethorough and complete and will convey the scope of the disclosure tothose skilled in the art. In the drawings, the sizes and relative sizesof layers and regions may be exaggerated for clarity. As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

In the specification, it will be understood that when an element such asa layer, region or substrate is referred to as being “on” anotherelement, it can be directly on the other element or intervening elementsmay be present. It will be understood that “an element A covers elementB” means that the element A is on the element B and does not necessarilymeans that the element A is on the entire portion of the element B. Thesame reference numerals or the same reference designators denote thesame elements throughout the specification.

The embodiments in the detailed description will be described withcross-sectional and perspective views as ideal views of the inventiveconcepts. Accordingly, shapes of the example embodiments may be modifiedaccording to manufacturing techniques and/or allowable errors.Therefore, the embodiments of the inventive concepts are not limited tothe specific shape illustrated in the drawings, but may include othershapes that may be formed according to manufacturing processes. It willbe also understood that although the terms first, second, third etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. These terms are only used to distinguish oneelement from another element. Example embodiments of aspects of thepresent inventive concepts explained and illustrated herein includetheir complementary counterparts.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to limit the inventive concepts. Asused herein, the singular terms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”,“comprising,”, “includes” and/or “including”, when used herein, specifythe presence of stated features, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, operations, elements, components, and/or groups thereof

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which the inventive concepts belong. Itwill be further understood that terms, such as those defined in commonlyused dictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andthis specification and will not be interpreted in an idealized or overlyformal sense unless expressly so defined herein.

Hereinafter, example embodiments of the inventive concepts will be fullydescribed with reference to the accompanying drawings.

FIG. 1A is a perspective view illustrating a semiconductor deviceaccording to some embodiments of the inventive concepts. FIG. 1B is across-sectional view taken along the lines I-I′, II-II′ and of FIG. 1A.FIGS. 1C and 1D are cross-sectional views taken along the line IV-IV′ ofFIG. 1A. FIGS. 2A and 2B are enlarged views of the portions ‘A’ and ‘B’of FIG. 1B, respectively. FIG. 3 is a cross-sectional view taken alongthe lines I-I′, and IV-IV of FIG. 1A to illustrate a semiconductordevice according to some embodiments of the inventive concepts.

Referring to FIGS. 1A, 1B, and 1C, an active pattern AP may be providedon a substrate 100. The substrate 100 may be a semiconductor substrate.For example, the substrate 100 may be a silicon substrate, a germaniumsubstrate, or a silicon-on-insulator (SOI) substrate. The active patternAP may extend in a first direction D1. In detail, a longitudinaldirection of the active pattern AP may extend in the first direction D1,and a transverse direction of the active pattern AP may extend in asecond direction D2 intersecting the first direction D1. In addition,the active pattern AP may protrude from the substrate 100 in a thirddirection D3 perpendicular to both the first direction D1 and the seconddirection D2. In some embodiments, the active pattern AP may be aportion of the substrate 100. In some embodiments, the active pattern APmay include an epitaxial layer grown from the substrate 100. In someembodiments, the epitaxial layer may include a plurality of epitaxiallayers having different lattice constants. Thus, a compressive strain ora tensile strain may be applied to the active pattern AP. One activepattern AP is illustrated in FIGS. 1A to 1C. However, the inventiveconcepts are not limited thereto. In some embodiments, a plurality ofactive patterns AP may be provided on the substrate 100. The pluralityof active patterns AP may be arranged along the second direction D2.

Device isolation patterns 102 may be disposed at both sides of theactive pattern AP. For example, the device isolation patterns 102 mayinclude silicon oxide, silicon nitride, and/or silicon oxynitride. Thedevice isolation patterns 102 may cover portions of sidewalls of theactive pattern AP. In other words, an upper portion of the activepattern AP may be exposed by the device isolation patterns 102. Theupper portion of the active pattern AP, which is exposed by the deviceisolation patterns 102, may be defined as an active fin AF. The activefin AF may be locally disposed under a gate structure GS.

The gate structure GS may be disposed on the substrate 100. The gatestructure GS may extend in the second direction D2 to intersect theactive pattern AP. The gate structure GS may cover portions of thesidewalls of the active pattern AP. In other words, the gate structureGS may intersect the active pattern AP and may cover a top surface andsidewalls of the active fin AF. Hereinafter, the active fin AF locallydisposed under the gate structure GS may be referred to as ‘a channelregion CH’. The gate structure GS may be provided in plurality. Theplurality of gate structures GS may be arranged along the firstdirection D1.

Gate spacers GSP may be disposed on sidewalls of the gate structures GS.The gate spacers GSP may extend along the sidewalls of the gatestructures GS in the second direction D2. According to some embodiments,the gate spacer GSP may include a first gate spacer SP1 adjacent to thegate structure GS and a second gate spacer SP1 disposed on a sidewall ofthe first gate spacer SP1. In other words, the second gate spacer SP2may be disposed on the sidewall of the gate structure GS with the firstgate spacer SP1 interposed therebetween. A thickness of the second gatespacer SP2 may be substantially equal to or greater than a thickness ofthe first gate spacer SP1. For example, the first gate spacer SP1 mayhave a thickness ranging from about 1 nm to about 10 nm, and the secondgate spacer SP2 may have a thickness ranging from about 1 nm to about 50nm. In some embodiments, the first and second gate spacers SP1 and SP2may include the same material. For example, the first and second gatespacers SP1 and SP2 may include a silicon nitride layer, a siliconoxynitride layer, or a silicon oxy-carbonitride layer. In someembodiments, the first and second gate spacers SP1 and SP2 may includedifferent materials. For example, the first gate spacer SP1 may includea silicon oxy-carbonitride layer, and the second gate spacer SP2 mayinclude a silicon nitride layer, or vice versa.

Each of the gate structures GS may include a gate electrode GE, a gatecapping pattern GP on the gate electrode GE, and a gate dielectricpattern GD between the gate electrode GE and the gate spacers GSP. Thegate dielectric pattern GD may also be disposed between the gateelectrode GE and the active fin AF and may horizontally extend from theactive fin AF to partially cover top surfaces of the device isolationpatterns 102. The gate dielectric pattern GD may extend along a bottomsurface of the gate electrode GE.

The gate electrode GE may include a conductive metal nitride (e.g.,titanium nitride or tantalum nitride) and/or a metal (e.g., aluminum ortungsten). The gate dielectric pattern GD may include at least one ofhigh-k dielectric layers. For example, the gate dielectric pattern GDmay include hafnium oxide, hafnium silicate, zirconium oxide, and/orzirconium silicate. The gate capping pattern GP may include, forexample, silicon nitride or silicon oxynitride.

Recess regions RS may be provided on the active pattern AP at both sidesof each of the gate structures GS. In some embodiments, one of therecess regions RS (e.g., the recess region RS on the active pattern APbetween the gate structures GS adjacent to each other) may be defined asa space between the channel regions CH locally disposed under the gatestructures GS. In other words, the one of the recess regions RS may havesidewalls defined by sidewalls, facing each other, of the channelregions CH adjacent to each other. Hereinafter, the recess region RS onthe active pattern AP between the adjacent gate structures GS will bemainly described for the purpose of ease and convenience in explanation.

According to the inventive concepts, the recess region RS may have aU-shaped cross-section having uppermost sidewalls that are substantiallyperpendicular to a top surface of the substrate 100 (i.e., a lowermostsurface of the gate structure GS). In detail, the recess region RS mayinclude an upper portion having a uniform width and a lower portionhaving a width becoming narrower toward a bottom surface of the recessregion RS, when viewed from a cross-section taken along the firstdirection D1. The upper portion of the recess region RS may be definedby first sidewalls S1 substantially perpendicular to the top surface ofthe substrate 100, and the lower portion of the recess region RS may bedefined by second sidewalls S2 and a bottom surface BS connected to thesecond sidewalls S2. The second sidewalls S2 may be rounded. The secondsidewalls S2 may be convex toward lower portions of the channel regionsCH adjacent to each other. Due to the shape of the recess region RS,each of the channel regions CH may include an upper sidewallsubstantially perpendicular to the top surface of the substrate 100, anda lower sidewall having a concave surface. One end of the upper sidewallof the channel region CH may be connected to a top surface of thechannel region CH. In some embodiments, the upper sidewall (i.e., thefirst sidewall S1) of the channel region CH may be aligned with thesidewall of the first gate spacer SP1 (i.e., outer surface of the firstgate spacer SP1). In other words, the upper sidewall of the channelregion CH and the sidewall of the first gate spacer SP1 adjacent theretomay be coplanar. However, embodiments of the inventive concepts are notlimited thereto.

Source/drain regions SD may be provided on inner surfaces of the recessregions RS, respectively. In other words, the source/drain regions SDmay be disposed on the active pattern AP at both sides of the gatestructure GS. In some embodiments, the source/drain regions SD mayinclude epitaxial layers that are formed using the active pattern AP,exposed by the recess regions RS, as a seed. For example, each of thesource/drain regions SD may include at least one of silicon-germanium(SiGe), silicon (Si) and silicon carbide (SiC) which are epitaxial-grownfrom the active pattern AP exposed by the recess region RS. Thus, thesource/drain regions SD may apply a compressive strain or a tensilestrain to the channel regions CH. The source/drain regions SD may bedoped with P-type or N-type dopants.

According to some embodiments, at least one of the source/drain regionsSD may include a plurality of epitaxial layers. For example, asillustrated in FIGS. 2A and 2B, at least one of the source/drain regionsSD may include a first epitaxial layer EP1 being in contact with theinner surface of the recess region RS, a second epitaxial layer EP2 onthe first epitaxial layer EP1, and a third epitaxial layer EP3 on thesecond epitaxial layer EP2. The first epitaxial layer EP1 may correspondto a buffer layer that is in contact with the active pattern AP. Thefirst epitaxial layer EP1 may be an epitaxial layer including alow-concentration semiconductor material. The second epitaxial layer EP2may correspond to a main layer extending from the first epitaxial layerEP 1 and may be an epitaxial layer including a high-concentrationsemiconductor material. The third epitaxial layer EP3 may correspond toa capping layer that is disposed on the second epitaxial layer EP2 toprotect the second epitaxial layer EP2. The third epitaxial layer EP3may be an epitaxial layer including a semiconductor material. Forexample, if the source/drain region SD includes silicon-germanium(SiGe), the first epitaxial layer EP1 may be a SiGe layer having a lowconcentration of germanium, the second epitaxial layer EP2 may be a SiGelayer having a high concentration of germanium, and the third epitaxiallayer EP3 may be a silicon layer.

Each of the source/drain regions SD may be in contact with the sidewallsS1 and S2 and the bottom surface BS of a corresponding recess region RS.The shape of the source/drain region SD may correspond to the shape ofthe recess region RS when viewed from a cross-section taken along thefirst direction D1. In more detail, the source/drain region SD may haveupper sidewalls substantially perpendicular to the top surface of thesubstrate 100 and lower sidewalls having convex surfaces when viewedfrom a cross-section taken along the first direction D1. The uppersidewalls of the source/drain region SD may be defined by the firstsidewalls S1 of the recess region RS, and the lower sidewalls of thesource/drain region SD may be defined by the second sidewalls S2 of therecess region RS. As a result, an interface between the active patternAP and the source/drain region SD may have a U-shaped cross-sectionhaving uppermost sidewalls that are substantially perpendicular to thetop surface of the substrate 100, when viewed from a cross-section takenalong the first direction D1. Each of the channel regions CH may havethe top surface higher than bottom surfaces of the source/drain regionsSD. Each of the channel regions CH may be disposed between thesource/drain regions SD when viewed from a plan view. In someembodiments, the source/drain regions SD may protrude upward from thetop surfaces of the channel regions CH.

Still referring to FIG. 1B, each of the source/drain regions SD mayinclude a first portion 122 exposed by the gate spacer GSP, and a secondportion 124 extending from the first portion 122 so as to be covered bythe gate spacer GSP. In other words, the first portion 122 may notvertically overlap with the gate spacer GSP, but the second portion 124may vertically overlap with the gate spacer GSP.

The first portion 122 may have first sidewalls SW1 and second sidewallsSW2 slanted with respect to the top surface of the substrate 100 whenviewed from a cross-section taken along the second direction D2. Thefirst sidewalls SW1 may diverge upwardly, and the second sidewalls SW2may converge upwardly. One end of the first sidewall SW1 may beconnected to one end of the second sidewall SW2. In some embodiments,the topmost end 122U of the first portion 122 may be higher than the topsurfaces of the active fins AF (i.e., the channel regions CH).

As illustrated in FIG. 1C, the second portion 124 may include a lowerportion LP having a first width W1 and an upper portion UP extend upwardfrom the lower portion LP when viewed from a cross-section taken alongthe second direction D2. In some embodiments, the first width W1 may besubstantially uniform throughout the lower portion LP. In someembodiments, the first width W1 may be gradually reduced as a distancefrom the substrate 100 increases. According to the inventive concepts,residual spacers 118 may be disposed between the second spacer SP2 andboth sidewalls of the lower portion LP when viewed from a cross-sectiontaken along the second direction D2. The residual spacers 118 may bedisposed on the device isolation patterns 102 disposed at both sides ofthe active pattern AP and may be in contact with the sidewalls of thelower portion LP. Thus, the both sidewalls of the lower portion LP inthe second direction D2 may not be in contact with the gate spacer SP2.The first width W1 of the lower portion LP, which is described above,may be defined as a distance between the residual spacers 118 facingeach other in the second direction D2. The residual spacers 118 mayinclude the same material as the first gate spacer SP1. For example, theresidual spacers 118 may include a silicon nitride layer, a siliconoxynitride layer, or a silicon oxy-carbonitride layer. The upper portionUP of the second portion 124 may be exposed by the residual spacers 118.In other words, the upper portion UP may be disposed at a higher levelthan top surfaces (or topmost ends) of the residual spacers 118. Theupper portion UP may be in contact with the second gate spacer SP2. Insome embodiments, the upper portion UP may include a first upper portionUP1 having a width increasing as a distance from the substrate 100increases, and a second upper portion UP2 having a width decreasing as adistance from the substrate 100 increases. In other words, sidewalls ofthe first upper portion UP1 may diverge upwardly, and sidewalls of thesecond upper portion UP2 may converge upwardly. The upper portion UP mayhave a second width W2 at a boundary between the first upper portion UP1and the second upper portion UP2. The second width W2 may correspond tothe maximum width of the upper portion UP. The second width W2 may begreater than the first width W1.

In some embodiments, a top surface 124U of the second portion 124 (i.e.,a top surface of the second upper portion UP2) may be substantiallyparallel to the top surface of the substrate 100. In addition, the topsurface 124U of the second portion 124 may be disposed at thesubstantially same height as the top surfaces of the channel regions CH.In this case, the upper portion UP of the second portion 124 may have afirst thickness dl . The thickness of the upper portion UP may bechanged. For example, if a thickness of the lower portion LP of thesecond portion 124 is reduced (i.e., heights of the top surfaces of theresidual spacers 118 are lowered) while the height of the top surface124U of the second portion 124 is fixed (i.e., the top surface 124U ofthe second portion 124 is disposed at the same height as the topsurfaces of the channel regions CH), the upper portion UP may have asecond thickness d2 greater than the first thickness dl, as illustratedin FIG. 1D. Volumes of the source/drain regions SD may be increased whenthe thickness of the upper portion UP is increased, so electricalcharacteristics of the semiconductor device may be improved.

In some embodiments, the top surface 124U of the second portion 124 maybe higher than the top surfaces of the channel regions CH. Asillustrated in FIG. 3, the top surface 124U (or the topmost end) of thesecond portion 124 may be higher than the top surfaces of the channelregions CH and may be lower than the topmost end 122U (or the topsurface) of the first portion 122. The upper portion UP of the secondportion 124 may have a third thickness d3 greater than the firstthickness dl. In this case, the thickness of the upper portion UP of thesecond portion 124 may also be increased. In addition, the second upperportion UP2 of the second portion 124 may have a wedge shape that isupwardly tapered.

A lower interlayer insulating layer 130 may be disposed on the substrate100 to cover the source/drain regions SD and the sidewalls of the gatestructures GS. A top surface of the lower interlayer insulating layer130 may be substantially coplanar with the top surfaces of the gatestructures GS. For example, the lower interlayer insulating layer 130may include at least one of a silicon oxide layer or low-k dielectriclayers. The lower interlayer insulating layer 130 may cover the deviceisolation patterns 102 exposed by the gate structures GS.

According to some embodiments, an upper interlayer insulating layer (notshown) may be disposed on the lower interlayer insulating layer 130. Theupper interlayer insulating layer may cover the top surfaces of the gatestructures GS. For example, the upper interlayer insulating layer mayinclude at least one of a silicon oxide layer, a silicon nitride layer,a silicon oxynitride layer, or low-k dielectric layers. First contactplugs (not shown) may penetrate the upper interlayer insulating layerand the lower interlayer insulating layer 130 so as to be electricallyconnected to the source/drain regions SD. A second contact plug (notshown) may penetrate the upper interlayer insulating layer and the lowerinterlayer insulating layer 130 so as to be electrically connected tothe gate electrode GE. Interconnections (not shown) may be disposed onthe upper interlayer insulating layer so as to be connected to the firstand second contact plugs. Operating voltages may be applied to thesource/drain regions SD and the gate electrode GE through theinterconnections and the first and second contact plugs. The first andsecond contact plugs and the interconnections may include a conductivematerial.

A three-dimensional (3D) field effect transistor according to someembodiments of the inventive concepts may use a plurality of surfaces ofthe active fin AF as a channel, unlike a two-dimensional (2D) fieldeffect transistor. In other words, the sidewall as well as the topsurface of the active fin AF may be used as the channel. Thus, a uniformsidewall profile of the active AF according to a height may directlyaffect characteristics of the semiconductor device. According to someembodiments of the inventive concepts, the interface between the activefin AF (i.e., the channel regions CH) and the source/drain region SD mayhave the U-shaped cross-section having uppermost sidewalls that aresubstantially perpendicular to the top surface of the substrate 100,when viewed from the cross-section taken along the first direction D1.In other words, a uniform junction profile may be realized between theactive fin AF and the source/drain region SD, so the electricalcharacteristics of the semiconductor device may be improved.

A method of manufacturing a semiconductor device according to someembodiments will be described hereinafter. FIGS. 4A, 5A, 6A, 7A, 8A, 9A,10A and 11A are perspective views illustrating a method of manufacturinga semiconductor device according to some embodiments of the inventiveconcepts. FIGS. 4B to 11B are cross-sectional views taken along thelines I-I′, II-II′, and III-III′ of FIGS. 4A to 11A, respectively. FIG.7C is a cross-sectional view taken along the lines I-I′, II-II′ andIII-III′ of FIG. 7A. FIG. 9C is an enlarged view of the portion ‘A’ ofFIG. 9B, and FIG. 9D is cross-sectional views taken along the linesI-I′, II-II′ and III-III′ of FIG. 9A.

Referring to FIGS. 4A and 4B, trenches 101 may be formed on a substrate100 to define an active pattern AP. The substrate 100 may be asemiconductor substrate. For example, the substrate 100 may be a siliconsubstrate, a germanium substrate, or a SOI substrate.

In some embodiments, the trenches 101 may be formed by patterning thesubstrate 100. In some embodiments, an epitaxial layer may be formed onthe substrate 100, and the epitaxial layer may be patterned to form thetrenches 101. The epitaxial layer may include a plurality of epitaxiallayers having different lattice constants, and a compressive strain or atensile strain may be applied to the active pattern AP. The patterningprocess for forming the trenches 101 may include forming a mask pattern(not shown) on the substrate 100, and performing an anisotropic etchingprocess using the mask pattern as an etch mask. The trenches 101 mayextend in a first direction D1 and may be spaced apart from each otherin a second direction D2 intersecting the first direction D1, so theactive pattern AP may extend in the first direction D1. In addition, theactive pattern AP may protrude from the substrate 100 in a thirddirection D3 perpendicular to both the first and second directions D1and D2. In some embodiments, a width of each of the trenches 101 maybecome narrower toward a bottom surface of each of the trenches 101, andthus, a width of the active pattern AP may become narrower toward a topsurface of the active pattern AP. One active pattern AP is illustratedin FIGS. 4A and 4B. However, the inventive concepts are not limitedthereto. In some embodiments, a plurality of the active patterns AP maybe arranged along the second direction D2.

Device isolation patterns 102 may be formed in the trenches 101. Thedevice isolation patterns 102 may be formed to expose an upper portionof the active pattern AP. The upper portion of the active pattern APexposed by the device isolation patterns 102 may be defined as an activefin AF. For example, device isolation patterns 102 may include siliconoxide, silicon nitride, and/or silicon oxynitride.

Referring to FIGS. 5A and 5B, an etch stop layer and a sacrificial gatelayer may be sequentially formed on the substrate 100 to cover theactive fin AF and the device isolation patterns 102. The etch stop layermay include, for example, a silicon oxide layer. The sacrificial gatelayer may include a material having an etch selectivity with respect tothe etch stop layer. The sacrificial gate layer may include, forexample, a poly-silicon layer.

The sacrificial gate layer may be patterned to form a sacrificial gatepattern 107. The sacrificial gate pattern 107 may extend in the seconddirection D2 to intersect the active pattern AP. Forming the sacrificialgate pattern 107 may include forming a gate mask pattern 109 on thesacrificial gate layer, and etching the sacrificial gate layer using thegate mask pattern 109 as an etch mask. The gate mask pattern 109 mayinclude, for example, silicon nitride. Etching the sacrificial gatelayer may include performing an etching process having an etchselectivity with respect to the etch stop layer.

After the formation of the sacrificial gate pattern 107, the etch stoplayer disposed at both sides of the sacrificial gate pattern 107 may beremoved to form an etch stop pattern 105 under the sacrificial gatepattern 107. The etch stop pattern 105 may extend along a bottom surfaceof the sacrificial gate pattern 107 to cover a top surface and sidewallsof the active fin AF and top surfaces of the device isolation patterns102. Here, the etch stop pattern 105, the sacrificial gate pattern 107,and the gate mask pattern 109 may be defined as a sacrificial gatestructure SGS. As illustrated in FIGS. 5A and 5B, more than twosacrificial gate structures SGS may be provided on the substrate 100.The sacrificial gate structures SGS may be arranged along the firstdirection D1.

Since the sacrificial gate pattern 107 is formed to intersect the activepattern AP, a first region R1 and second regions R2 may be defined inthe active pattern AP. The first region R1 may correspond to a portionof the active pattern AP which is disposed under the sacrificial gatestructure SGS and overlaps with the sacrificial gate structure SGS. Thesecond regions R2 may correspond to other portions of the active patternAP which are disposed at both sides of the sacrificial gate structureSGS and are horizontally separated from each other by the first regionR1. The first region R1 may vertically overlap with a first gate spacerSP1 of FIGS. 6A and 6B.

A first gate spacer layer 112 may be formed on the substrate 100 toconformally cover the sacrificial gate structures SGS. The first gatespacer layer 112 may have a substantially uniform thickness asillustrated in FIG. 5A. The first gate spacer layer 112 may cover topsurfaces of the device isolation patterns 102 disposed at both sides ofthe sacrificial gate structure SGS, top surfaces and sidewalls of thesecond regions R2 disposed at both sides of the sacrificial gatestructure SGS, and a top surface and sidewalls of the sacrificial gatestructure SGS. For example, the first gate spacer layer 112 may beformed to have a thickness of about 1 nm to about 10 nm. The first gatespacer layer 112 may include, for example, a silicon nitride layer, asilicon oxynitride layer, or a silicon oxy-carbonitride layer. The firstgate spacer layer 112 may be formed by a deposition process such as achemical vapor deposition (CVD) process or an atomic layer deposition(ALD) process.

Referring to FIGS. 6A and 6B, the first gate spacer layer 112 may bepatterned to form first gate spacers SP1 on sidewalls of the sacrificialgate structures SGS. The first gate spacer layer 112 may be patternedusing, for example, an anisotropic etching process. The top surfaces ofthe second regions R2 of the active pattern AP and the top surfaces ofthe device isolation patterns 102 may be exposed by the anisotropicetching process. A portion of the gate mask pattern 109 may be etchedduring the anisotropic etching process. After the anisotropic etchingprocess, a residual portion of the gate mask pattern 109 may remain onthe sacrificial gate pattern 107. In addition, portions of the firstgate spacer layer 112 may remain on both sidewalls of each of the secondregions R2.

Subsequently, upper portions of the active pattern AP at both sides ofeach of the sacrificial gate structures SGS may be removed. In otherwords, portions of the second regions R2 of the active pattern AP may beremoved. Removing the portions of the second regions R2 may be performedusing an anisotropic etching process. Thus, first preliminary recessregions 113 may be formed in the active pattern AP at both sides of eachof the sacrificial gate structures SGS. The sacrificial gate structuresSGS and the first gate spacers SP1 may be used as an etch mask for theanisotropic etching process. Bottom surfaces of the first preliminaryrecess regions 113 may be defined by recessed top surfaces of the secondregions R2. In some embodiments, the recessed top surfaces of the secondregions R2 may be lower than a top surface of the first region R1 andmay be higher than the top surfaces of the device isolation patterns 102as illustrated in FIG. 6A. If the top surfaces of the device isolationpatterns 102 are curved surfaces, the recessed top surfaces of thesecond regions R2 may be higher than the topmost ends of the deviceisolation patterns 102. Recessed depths of the second regions R2 may bevaried. Sidewalls of the first preliminary recess regions 113 may bealigned with outer surfaces of the first gate spacers SP1. The sidewallsof the first preliminary recess regions 113 may be spaced apart from thesides of each of the sacrificial gate structures SGS by the thickness ofthe first gate spacer layer 112 (e.g., about 1 nm to 10 nm). In someembodiments, the sidewalls of the first preliminary recess regions 113may be substantially perpendicular to the top surface of the substrate100 (i.e., a lowermost surface of the sacrificial gate structures SGS)as illustrated in FIG. 6B.

In some embodiments, removing the portions of the second regions R2 mayinclude etching the second regions R2 using an etch recipe having arelatively high etch-selectivity with respect to the first gate spacerlayer 112. In other words, an etched amount of the first gate spacerlayer 112 may be relatively small during the etching process forremoving the portions of the second regions R2. Thus, residual portionsof the first gate spacer layer 112 may remain on sidewalls of therecessed second regions R2 after the etching process. The residualportions of the first gate spacer layer 112 may be referred to as ‘finspacers FS’. In some embodiments, top surfaces (or the topmost ends) ofthe fin spacers FS may be higher than the recessed top surfaces of thesecond regions R2 and lower than the top surfaces of the first regionsR1. Heights of the top surfaces of the fin spacers FS may be variedaccording to recessed depths of the second regions R2 and/or a processrecipe (e.g., an etch-selective ratio) of the etching process forremoving the portions of the second regions R2. The first gate spacersSP1 and the gate mask patterns 109 may be partially etched during theetching process for removing the portions of the second regions R2.

Referring to FIGS. 7A and 7B, sacrificial filling patterns 114 may beformed in the first preliminary recess regions 113, respectively. Thesacrificial filling patterns 114 may be formed of a material having anetch selectivity with respect to the active pattern AP. In someembodiments, an etch rate of the sacrificial filling patterns 114 by anetchant may be higher than an etch rate of the active pattern AP by theetchant. For example, if the active pattern AP includes silicon (Si),the sacrificial filling patterns 114 may be formed of silicon-germanium(SiGe). At this time, a germanium concentration of the sacrificialfilling pattern 114 may be in a range of about 5 atm % to about 30 atm%. However, the inventive concepts are not limited thereto. Thegermanium concentration may be variously controlled to realize a desiredratio of the etch rate of the sacrificial filling patterns 114 to theetch rate of the active pattern AP.

According to some embodiments, the sacrificial filling pattern 114 maybe formed by an epitaxial growth process. In other word, the sacrificialfilling pattern 114 may be formed by a selective epitaxial growth (SEG)process using the active pattern AP, exposed by each of the firstpreliminary recess regions 113, as a seed. In some embodiments, thesacrificial filling pattern 114 may fill an entire portion of the firstpreliminary recess region 113. Thus, a top surface of the sacrificialfilling pattern 114 may be disposed at the same height as or a higherheight than the top surface of the first region R1. The top surface ofthe sacrificial filling pattern 114 may be substantially coplanar withthe top surface of the substrate 100 as illustrated in FIG. 7B. However,the inventive concepts are not limited thereto. In some embodiments, thesacrificial filling patterns 114 may partially fill the respective firstpreliminary recess regions 113. A lower portion of the sacrificialfilling pattern 114 may be in contact with the fin spacers FS, and anupper portion of the sacrificial filling pattern 114 may be disposed ata higher level than the top surfaces of the fin spacers FS. A width, inthe second direction D2, of the lower portion of the sacrificial fillingpattern 114 may correspond to a distance between the fin spacers FS. Theupper portion of the sacrificial filling pattern 114 may havewedge-shaped sidewalls that are laterally tapered. The maximum width ofthe upper portion of the sacrificial filling pattern 114 may be greaterthan the width of the lower portion of the sacrificial filling pattern114. The shape of the upper portion of the sacrificial filling pattern114 may be the substantially same as the shape of the upper portion UPof the second portion 124 of the source/drain region SD described withreference to FIG. 1C.

In some embodiments, the sacrificial filling pattern 114 may protrudeupward from the top surface of the first region R1, and the top surfaceof the sacrificial filling pattern 114 may have an upwardly taperedwedge-shape as illustrated in FIG. 7C. In this case, the shape of theupper portion of the sacrificial filling pattern 114 may be thesubstantially same as the shape of the upper portion UP of the secondportion 124 of the source/drain region SD described with reference toFIG. 3. The shape of the sacrificial filling pattern 114 may varyaccording to the recessed depth of the second region R2, the height ofthe fin spacer FS, and/or a grown amount of the sacrificial fillingpattern 114. Hereinafter, the resultant structure of FIGS. 7A and 7Bwill be described as an example for the purpose of ease and conveniencein explanation. However, the inventive concepts are not limited thereto.The following processes of the manufacture method may also be applied tothe resultant structure of FIG. 7C.

Referring to FIGS. 8A and 8B, a second gate spacer layer 116 may beconformally formed on the resultant structure of FIGS. 7A and 7B. Inother word, the second gate spacer layer 116 may conformally cover theresultant structure having the sacrificial filling patterns 114. Athickness of the second gate spacer layer 116 may be equal to or greaterthan that of the first gate spacer layer 112. For example, the thicknessof the second gate spacer layer 116 may be in a range of about 1 nm toabout 50 nm. In some embodiments, the second gate spacer layer 116 maybe formed of the same material as the first gate spacer layer 112. Forexample, the second gate spacer layer 116 may include a silicon nitridelayer, a silicon oxynitride layer, or a silicon oxy-carbonitride layer.In some embodiments, the second gate spacer layer 116 may be formed of adifferent material from the first gate spacer layer 112. For example,the first gate spacer layer 112 may include a silicon oxy-carbonitridelayer, and the second gate spacer layer 116 may include a siliconnitride layer. The second gate spacer layer 116 may be formed by thesame method as the first gate spacer layer 112.

Referring to FIGS. 9A and 9B, the second gate spacer layer 116 may bepatterned to form a second gate spacer SP2 on the sidewall of the firstgate spacer SP1. The second gate spacer layer 116 may be patterned usingan anisotropic etching process. The top surfaces of the sacrificialfilling patterns 114 and the top surfaces of the device isolationpatterns 102 may be exposed by the anisotropic etching process. Thefirst and second gate spacers SP1 and SP2 may be defined as a gatespacer GSP.

Recess regions RS may be formed in the active pattern AP at both sidesof each of the sacrificial gate structures SGS as illustrated in FIG.9B. According to some embodiments, forming the recess regions RS mayinclude performing a series of etching processes including ananisotropic etching process and an isotropic etching process using thesacrificial gate structures SGS and the first and second gate spacersSP1 and SP2 as an etch mask. The sacrificial filling pattern 114 may beetched in a depth direction by the anisotropic etching process to exposethe second region R2 of the active pattern AP. In addition, thesacrificial filling pattern 114 may also be etched in a lateraldirection toward the active fin AF by the isotropic etching process. Insome embodiments, the sacrificial filling pattern 114 may be entirelyetched as illustrated in FIG. 9B such that the sidewalls of the firstpreliminary recess regions 113 of FIG. 6B may be exposed. In someembodiments, the sacrificial filling pattern 114 may partially remain.The second region R2 of the active pattern AP may also be etched in thedepth direction and in the lateral direction toward the active fin AF bythe anisotropic etching process and the isotropic etching process. As aresult, the recess region RS having an undercut region 120 disposedunder the gate spacer GSP may be formed. In some embodiments, thesacrificial filling pattern 114 may be etched faster than the secondregion R2 of the active pattern AP during the series of etchingprocesses, and the recess region RS may thus have a U-shapedcross-section having uppermost sidewalls that are substantiallyperpendicular to the top surface of the substrate 100 (i.e., a lowermostsurface of the sacrificial gate structures SGS) as illustrated in FIG.9B.

As appreciated by the present inventors, if the sacrificial fillingpattern 114 is not formed on the second region R2 of the active patternAP, the recess region RS may not have a U-shaped cross-section havinguppermost sidewalls that are substantially perpendicular to the topsurface of the substrate 100. FIG. 9C is an enlarged view of the portion‘A’ of FIG. 9B. As illustrated in FIG. 9C, if the sacrificial fillingpattern 114 is not formed, the second region R2 of the active pattern APmay be etched by a series of etching processes including an anisotropicetching process and an isotropic etching process to form a recess regionRSa. Etchants of the series of etching processes may not easily reach toa portion of the active pattern AP disposed immediately beneath the gatespacer GSP, and the portion of the active pattern AP disposedimmediately beneath the gate spacer GSP may remain as marked by circle Cin FIG. 9C. It will be understood that a portion of the sacrificialfilling pattern 114 disposed immediately beneath the gate spacer GSP maybe etched even though only limited amount of the etchants reach to theportion of the sacrificial filling pattern 114 since the etchants mayetch the sacrificial filling pattern 114 faster than the active patternAP.

Referring again to FIG. 9B, the recess region RS may have an upperportion having a uniform width and a lower portion having a widthbecoming narrower toward a bottom surface of the recess region RS, whenviewed from a cross-section taken along the first direction D1. Theupper portion of the recess region RS may be defined by first sidewallsS1 substantially perpendicular to the top surface of the substrate 100,and the lower portion of the recess region RS may be defined by secondsidewalls S2 and a bottom surface BS connected to the second sidewallsS2. The first sidewall Si of the recess region RS may be recessed towardthe sacrificial gate structure SGS relative to an outer surface of thesecond gate spacers SP2 as illustrated in FIG. 9B. The second sidewallsS2 may be rounded. The second sidewalls S2 may have convex surfacestoward lower portions of the active fins AF adjacent to each other. Thebottom surface BS of the recess region RS may be disposed at thesubstantially same level as the top surfaces (or the topmost ends) ofthe device isolation patterns 102. However, the inventive concepts arenot limited thereto. The undercut region 120 may have the substantiallysame shape as the second portion 124 of the source/drain region SDdescribed with reference to FIG. 1C. The shape of the undercut region120 may be changed according to the shape of the sacrificial fillingpattern 114 described above.

The second gate spacer layer 116 and the fin spacers FS disposed on thesidewalls of the second region R2 may be removed during the formation ofthe recess regions RS. In some embodiments, the second gate spacer layer116 disposed on the sidewalls of the second regions R2 may be completelyremoved, but portions of the fin spacers FS may remain under the secondgate spacers SP2. After the formation of the recess regions RS, theportions of the fin spacers FS remaining under the second gate spacersSP2 may be defined as residual spacers 118. The gate mask pattern 109and the first and second gate spacers SP1 and SP2 may partially etchedduring the formation of the recess regions RS.

FIG. 9D is cross-sectional views taken along the lines I-I′, II-II′, andIII-III′ of FIG. 9A. Referring to FIG. 9D, portions of the sacrificialfilling pattern 114 that are beneath the second gate spacers SP2 may notbe removed by a series of etching processes including an anisotropicetching process and an isotropic etching process that are performed toremove the sacrificial filling pattern 114 and the second region R2 ofthe active pattern AP. Accordingly, preliminary recess regions PRS maybe formed at both sides of each of the sacrificial gate structures SGS.The preliminary recess region PRS may extend through the sacrificialfilling pattern 114. The portions of the sacrificial filling pattern 114that remain beneath the second gate spacers SP2 may be removed byperforming an isotropic etching process that selectively removes thesacrificial filling pattern 114 to form the recess regions RS of FIG.9B. For example, the active pattern AP may include silicon (Si), thesacrificial filling pattern 114 may include silicon-germanium (SiGe),and the isotropic etching process may be a wet etching process using anetchant that includes peracetic acid (C₂H₄O₃) and hydrofluoric acid(HF). The etchant including peracetic acid (C₂H₄O₃) and hydrofluoricacid (HF) may etch the sacrificial filling pattern 114 includingsilicon-germanium about 10 to about 100 times faster than the activepattern AP including silicon. The etch rate of the sacrificial fillingpattern 114 including silicon-germanium may vary according to agermanium content of the sacrificial filling pattern 114.

Referring to FIGS. 10A and 10B, source/drain regions SD may be formed oninner surfaces of the recess regions RS, respectively. According to someembodiments, the source/drain regions SD may be formed by a SEG processusing the active pattern AP, exposed by the recess regions RS, as aseed. In some embodiments, each of the source/drain regions SD mayinclude an epitaxial layer. For example, each of the source/drainregions SD may include at least one of silicon-germanium (SiGe), silicon(Si) and silicon carbide (SiC) which are epitaxial-grown from the activepattern AP exposed by the recess region RS. Thus, the source/drainregions SD may apply a compressive strain or a tensile strain to theactive fins AF. The source/drain regions SD may be doped with dopantsduring or after the SEG process. The source/drain regions SD may bedoped with P-type or N-type dopants.

According to some embodiments, at least one of the source/drain regionsSD may be formed of a multi-layered epitaxial layer, as described withreference to FIGS. 2A and 2B. In other word, at least one of thesource/drain regions SD may include first, second and third epitaxiallayers EP1, EP2 and EP3 which are sequentially formed. The first tothird epitaxial layers EP1, EP2 and EP3 may be continuously formed inthe same chamber.

Each of the source/drain regions SD may fully fill the recess region RSincluding the undercut region 120. In some embodiments, the source/drainregions SD may protrude upward from the top surface of the active finAF. A shape of each of the source/drain regions SD may correspond to theshape of the recess region RS, when viewed from a cross-section takenalong the first direction Dl. In more detail, each of the source/drainregions SD may have upper sidewalls substantially perpendicular to thetop surface of the substrate 100 and lower sidewalls having convexsurfaces toward the channel regions CH, when viewed from a cross-sectiontaken along the first direction D1. The upper sidewalls of thesource/drain region SD may be defined by the first sidewalls S1 of therecess region RS, and the lower sidewalls of the source/drain region SDmay be defined by the second sidewalls S2 of the recess region RS. Thefirst sidewalls S1 may be recessed toward the sacrificial gatestructures SGS relative to the outer surface of the second gate spacersSP2. As a result, an interface of the active pattern AP and thesource/drain region SD may have a U-shaped cross-section havinguppermost portions that are substantially perpendicular to the topsurface of the substrate 100, when viewed from a cross-section takenalong the first direction D1. This means that electrical characteristicsof the semiconductor device may be improved. In some embodiments, thefirst sidewalls S1 may be aligned with the outer surface of the firstgate spacers SP1 as illustrated in FIG. 10B.

Each of the source/drain regions SD may include a first portion 122exposed by the gate spacers GSP, and second portions 124 extending fromthe first portion 122 as illustrated in FIG. 10B. The second portions124 may be covered by the gate spacers GSP. In other word, the firstportion 122 may not vertically overlap with the gate spacers GSP, butthe second portions 124 may vertically overlap with the gate spacersGSP. In other word, the second portion 124 may correspond to a portionof the source/drain region SD that fills the undercut region 120. Thus,a shape of the second portion 124 may correspond to the shape of theundercut region 120.

The first portion 122 may have first sidewalls SW1 and second sidewallsSW2 slanted with respect to the top surface of the substrate 100 whenviewed from a cross-section taken along the second direction D2. Thefirst sidewalls SW1 may diverge toward the topmost end 122U of the firstportion 122 and the second sidewalls SW2 may converge toward the topmostend 122U of the first portion 122 as illustrated in FIG. 10B. One end ofthe first sidewall SW1 may be connected to one end of the secondsidewall SW2. In some embodiments, the topmost end 122U of the firstportion 122 may be higher than the top surfaces of the active fins AF.

Referring to FIGS. 11A and 11B, a lower interlayer insulating layer 130may be formed on the substrate 100 having the source/drain regions SD.The lower interlayer insulating layer 130 may be formed to cover thesource/drain regions SD and the sacrificial gate structures SGS. Thelower interlayer insulating layer 130 may include a silicon oxide layer,a silicon nitride layer, a silicon oxynitride, and/or low-k dielectriclayers.

The gate mask patterns 109, the sacrificial gate patterns 107, and theetch stop patterns 105 may be removed to form gap regions 140 of whicheach is disposed between the gate spacers GSP. The gap region 140 mayexpose the active fin AF. During the removal of the gate mask pattern109, a portion of the lower interlayer insulating layer 130 may also beetched. Forming the gap region 140 may include performing an etchingprocess having an etch selectivity with respect to the gate spacers GSP,the lower interlayer insulating layer 130 and the etch stop pattern 105to etch the sacrificial gate pattern 107. In addition, forming the gapregion 140 may include removing the etch stop pattern 105 to expose theactive fin AF.

Referring again to FIGS. 1A and 1B, a gate dielectric pattern GD and agate electrode GE may be formed to fill each of the gap regions 140. Indetail, a gate dielectric layer (not shown) may be formed on thesubstrate 100 including the gap regions 140 to partially fill the gapregions 140. The gate dielectric layer may be formed to cover the activefin AF exposed through the gap regions 140. The gate dielectric layermay include at least one of high-k dielectric layers. For example, thegate dielectric layer may include hafnium oxide, hafnium silicate,zirconium oxide, and/or zirconium silicate. The gate dielectric layermay be formed by performing an ALD process or a CVD process. A gatelayer (not shown) may be formed on the gate dielectric layer to fill thegap regions 140. The gate layer may include a conductive metal nitride(e.g., titanium nitride, tantalum nitride, or tungsten nitride) and/or ametal (e.g., aluminum or tungsten). The gate layer and the gatedielectric layer may be planarized to form the gate dielectric patternsGD and the gate electrodes GE. Top surfaces of the lower interlayerinsulating layer 130 and the gate spacers GSP may be exposed by theplanarization process. The gate dielectric pattern GD may extend along abottom surface of the gate electrode GE and may also extend on bothsidewalls of the gate electrode GE so as to be disposed between the gateelectrode GE and the gate spacers GSP.

An upper portion of the gate electrode GE may be recessed. An upperportion of the gate dielectric pattern GD may also be removed when thegate electrode GE is recessed. A gate capping pattern GP may be formedin a spaced formed by removing the upper portions of the gate electrodeGE and the gate dielectric pattern GD. The gate capping pattern GP mayinclude, for example, silicon nitride. The gate dielectric pattern GD,the gate electrode GE, and the gate capping pattern GP may be defined asa gate structure GS. The gate structure GS may extend in the seconddirection D2.

An upper interlayer insulating layer (not shown) may be formed on thesubstrate 100 including the gate structure GS. The upper interlayerinsulating layer may include a silicon oxide layer, a silicon nitridelayer, and/or a silicon oxynitride layer. First contact holes (notshown) may be formed to penetrate the upper interlayer insulating layerand the lower interlayer insulating layer 130. The first contact holesmay expose the source/drain regions SD. Upper portions of thesource/drain regions SD may be partially removed by an etching processfor forming the first contact holes. A second contact hole (not shown)may be formed to penetrate the upper interlayer insulating layer and thelower interlayer insulating layer 130. The second contact hole mayexpose the gate electrode GE. Thereafter, first contact plugs may beformed to fill the first contact holes, respectively, and a secondcontact plug may be formed to fill the second contact hole.Interconnections connected to the first and second contact plugs may beformed on the upper interlayer insulating layer. Operating voltages maybe applied to the source/drain regions SD and the gate electrode GEthrough the interconnections and the first and second contact plugs. Thefirst and second contact plugs and the interconnections may include aconductive material.

FIG. 12A are cross-sectional views taken along the lines I-I′, II-II′,and III-III′ of FIG. 1A to illustrate a semiconductor device accordingto some embodiments of the inventive concepts. FIG. 12B is across-sectional view taken along the line IV-IV′ of FIG. 1A.

Referring to FIGS. 12A and 12B, each of recess regions RS may have arectangular shape or a shape similar to a rectangular shape when viewedfrom a cross-section taken along the first direction D1. For example,each of the recess regions RS may include first sidewalls S1substantially perpendicular to the top surface of the substrate 100,second sidewalls S2 slanted with respect to the top surface of thesubstrate 100, and a bottom surface BS substantially parallel to the topsurface of the substrate 100. The second sidewalls S2 may be very shortor may not be formed. The bottom surface BS may be disposed at thesubstantially same level as the top surfaces (or the topmost ends) ofthe device isolation patterns 102.

Source/drain regions SD may be provided on inner surfaces of the recessregions RS, respectively. Each of the source/drain regions SD may fullyfill the recess region RS. Shapes of the source/drain regions SD maycorrespond to the shapes of the recess regions RS when viewed from across-section taken along the first direction D1. An interface betweenthe active pattern AP and the source/drain region SD may have arectangular shape or a shape similar to a rectangular shape when viewedfrom a cross-section taken along the first direction D1. Thus, a uniformjunction profile may be realized between the active fin AF (i.e., thechannel region CH) and the source/drain region SD. In some embodiments,the source/drain regions SD may protrude from the top surfaces of thechannel regions CH.

Each of the source/drain regions SD may include a first portion 122exposed by the gate spacers GSP, and second portions 124 extending fromthe first portion 122 and covered by the gate spacers GSP. Shapes of thefirst and second portions 122 and 124 may be the substantially same asor similar to corresponding shapes described with reference to FIGS. 1Band 1C, when viewed from a cross-section taken along the seconddirection D2. In other word, the first portion 122 may have firstsidewalls SW1 and second sidewalls SW2 slanted with respect to the topsurface of the substrate 100 when viewed from a cross-section takenalong the second direction D2. When viewed from a cross-section takenalong the second direction D2, the second portion 124 may include alower portion LP having a first width W1, a first upper portion UP 1extending from the lower portion LP and having a width increasing as adistance from the substrate 100 increases, and a second upper portionUP2 extending from the first upper portion UP1 and having a widthdecreasing as a distance from the substrate 100 increases. The first andsecond upper portions UP1 and UP2 may constitute an upper portion UP ofthe second portion 124. The upper portion UP of the second portion 124may have a second width W2 corresponding to the maximum width at aboundary between the first and second upper portions UP1 and UP2. Thesecond width W2 may be greater than the first width W1. The lowerportion LP of the second portion 124 may be in contact with the residualspacers 118, and the upper portion UP of the second portion 124 may beexposed by the residual spacers 118. In other word, the upper portion UPof the second portion 124 may be disposed at a higher level than the topsurfaces (or the topmost ends) of the residual spacers 118 and may be incontact with the second gate spacer SP2. Other elements of thesemiconductor device illustrated in FIGS. 12A and 12B may be the same asor similar to corresponding elements of the semiconductor devicedescribed with reference to FIGS. 1A, 1B, and 1C.

FIG. 13 are a cross-sectional views taken along the lines I-I′,III-III′, and IV-IV′ of FIG. 1A to illustrate a semiconductor deviceaccording to some embodiments of the inventive concepts. For the purposeof ease and convenience in explanation, the descriptions to the sameelements as in the above embodiments will be omitted or mentionedbriefly.

Referring to FIG. 13, recess regions RS may extend downward to havebottom surfaces lower than the top surfaces (or the topmost ends) of thedevice isolation patterns 102. In more detail, each of the recessregions RS may have first sidewalls Si substantially perpendicular tothe top surface of the substrate 100, second sidewalls S2 slanted withrespect to the top surface of the substrate 100, third sidewalls S3substantially perpendicular to the top surface of the substrate 100, anda bottom surface BSa substantially parallel to the top surface of thesubstrate 100. The second sidewalls S2 may converge toward the bottomsurface BSa. Here, the bottom surface BSa may be disposed at a lowerlevel than the top surfaces (or the topmost ends) of the deviceisolation patterns 102. The third sidewalls S3 may be provided betweenthe bottom surface BSa and the second sidewalls S2 so as to be connectto the bottom surface BSa and the second sidewalls S2. In someembodiments, the second sidewalls S2 may be omitted, and the thirdsidewalls S3 may be connected directly to the first sidewalls S1.

Source/drain regions SD may be provided on inner sidewalls of the recessregions RS, respectively. Each of the source/drain regions SD may fullyfill each of the recess regions SD. Shapes of the source/drain regionsSD may correspond to the shapes of the recess regions RS when viewedfrom a cross-section taken along the first direction Dl. In someembodiments, the source/drain regions SD may protrude from the topsurfaces of the channel regions CH. Each of the source/drain regions SDmay include a first portion 122 exposed by the gate spacers GSP, andsecond portions 124 extending from the first portion 122 and covered bythe gate spacers GSP.

The first portion 122 may have first sidewalls SW1 and second sidewallsSW2 that are slanted with respect to the top surface of the substrate100 and third sidewalls SW3 connected to the first sidewalls SW1, whenviewed from a cross-section taken along the second direction D2. Thethird sidewalls SW3 may be in contact with the device isolation patterns102. A shape of the second portion 124 may be the substantially same asor similar to the shape of the second portion 124 described withreference to FIGS. 1B and 1C, when viewed from a cross-section takenalong the second direction D2.

Hereinafter, a method of manufacturing a semiconductor device accordingto some embodiments of the inventive concepts will be described. FIGS.14 to 21 are cross-sectional views taken along the lines I-I′, II-II′,and III-III′ of FIG. 1A to illustrate a method of manufacturing asemiconductor device according to some embodiments of the inventiveconcepts.

Referring to FIG. 14, second preliminary recess regions 117 may beformed in the active pattern AP. Forming the second preliminary recessregions 117 may include performing an etching process on the structureillustrated in FIGS. 5A and 5B. The etching process for forming thesecond preliminary recess regions 117 may include anisotropicallyetching the first gate spacer layer 112 to expose the top surfaces ofthe second regions R2, and anisotropically etching the exposed topsurfaces of the second regions R2 using the sacrificial gate structuresSGS and the first gate spacers SP1 as an etch mask. The anisotropicetching of the first gate spacer layer 112 and the anisotropic etchingof the top surfaces of the second regions R2 may be performed by amethod which is the substantially same as or similar to the methoddescribed with reference to FIGS. 6A and 6B. Recessed depths of thesecond preliminary recess regions 117 may be greater than those of thefirst preliminary recess regions 113 described with reference to FIGS.6A and 6B.

Each of the second preliminary recess regions 117 may have firstsidewalls S1 substantially perpendicular to the top surface of thesubstrate 100, second sidewalls S2 slanted with respect to the topsurface of the substrate 100, and a bottom surface BS substantiallyparallel to the top surface of the substrate 100. The second sidewallsS2 may be very short or may not be formed, and thus, the secondpreliminary recess region 117 may have a cross-section having arectangular shape or a shape similar to a rectangular shape. The bottomsurface BS may be disposed at the substantially same level as the topsurfaces (or the topmost ends) of the device isolation patterns 102.After the formation of the second preliminary recess regions 117, firstgate spacers SP1 may be formed on the sidewalls of the sacrificial gatestructure SGS, and portions of the first gate spacer layer 112 mayremain on the sidewalls of the second region R2 to form fin spacers FS.

Referring to FIG. 15, a sacrificial filling pattern 114 may be formed ineach of the second preliminary recess regions 117. A material and amethod of forming the sacrificial filling patterns 114 may be the sameas or similar to those described with reference to FIGS. 7A and 7B. Thesacrificial filling pattern 114 may fully fill the second preliminaryrecess region 117 as illustrated in FIG. 15. Thus, a top surface of thesacrificial filling pattern 114 may be disposed at the same height as ora higher height than the top surface of the first region R1. In someembodiments, the sacrificial filling pattern 114 may not fully fill thesecond preliminary recess region 117. A lower portion of the sacrificialfilling pattern 114 may be in contact with the fin spacers FS, and anupper portion of the sacrificial filling pattern 114 may be disposed ata higher level than the top surfaces of the fin spacers FS. A width, inthe second direction D2, of the lower portion of the sacrificial fillingpattern 114 may correspond to a distance between the fin spacers FS. Theupper portion of the sacrificial filling pattern 114 may havewedge-shaped sidewalls that are laterally tapered. The maximum width ofthe upper portion of the sacrificial filling pattern 114 may be greaterthan the width of the lower portion of the sacrificial filling pattern114. In some embodiments, the sacrificial filling pattern 114 mayprotrude upward form the top surface of the first region R1, asdescribed with reference to FIG. 7C.

Referring to FIG. 16, a second gate spacer layer 116 may be conformallyformed on the resultant structure of FIG. 15. In other word, the secondgate spacer layer 116 may conformally cover the resultant structurehaving the sacrificial filling patterns 114. A material and a thicknessof the second gate spacer layer 116 may be the same as or similar tothose described with reference to FIGS. 8A and 8B.

Referring to FIG. 17, the second gate spacer layer 116 may be patternedto form a second gate spacer SP2 on the sidewall of the first gatespacer SP1. The second gate spacer layer 116 may be patterned using ananisotropic etching process. The top surfaces of the sacrificial fillingpatterns 114 and the top surfaces of the device isolation patterns 102may be exposed by the anisotropic etching process.

Next, portions of the sacrificial filling patterns 114 may be removed toform third preliminary recess regions 119 at both sides of thesacrificial gate structure SGS. Removing the portions of the sacrificialfilling patterns 114 may be performed using an anisotropic etchingprocess using the sacrificial gate structure SGS and the first andsecond gate spacers SP1 and SP2 as an etch mask. In some embodiments,the anisotropic etching process for removing the portions of thesacrificial filling patterns 114 may be performed using an etch recipehaving a relatively low etch-selectivity with respect to the second gatespacer layer 116. In other word, the second gate spacer layer 116 may beetched during the etching process for removing the sacrificial fillingpattern 114. Thus, the second gate spacer layer 116 and the fin spacersFS, which are disposed on the sidewalls of the second regions R2, may beremoved during the formation of the third preliminary recess regions119. In some embodiments, the second gate spacer layer 116 on thesidewalls of the second regions R2 may be completely removed, but thefin spacers FS may not be completely removed. In other word, portions ofthe fin spacers FS may remain under the second gate spacers SP2. Afterthe formation of the third preliminary recess regions 119, the portionsof the fin spacers FS remaining under the second gate spacers SP2 may bedefined as residual spacers (e.g., 118 of FIG. 12B). The gate maskpattern 109 and the first and second gate spacers SP1 and SP2 may bepartially etched during the formation of the third preliminary recessregions 119.

In some embodiments, the third preliminary recess regions 119 may notexpose the sidewalls S1 and S2 and the bottom surface BS of the secondpreliminary recess regions 117 as illustrated in FIG. 17. In other word,a portion of the sacrificial filling pattern 114 may remain on thesidewalls S1 and S2 and the bottom surface BS of the second preliminaryrecess region 117, and the third preliminary recess regions 119 mayexpose the sacrificial filling pattern 114. However, the inventiveconcepts are not limited thereto. In some embodiments, the bottomsurfaces of the second preliminary recess regions 117 may be exposed bythe anisotropic etching process. In some embodiments, the thirdpreliminary recess regions 119 may further extend downward beyond thetop surfaces of the device isolation patterns 102 and may extend throughthe sacrificial filling pattern 114, as illustrated in FIG. 18. Bottomsurfaces BSa of the third preliminary recess regions 119 may be disposedat a lower level than the top surfaces (or the topmost ends) of thedevice isolation patterns 102. The third preliminary recess regions 119may have sidewalls that are aligned with the outer sidewalls of thesecond gate spacers SP2 and extend in a depth direction so as to beconnected to the bottom surface BSa. Hereinafter, the structure of FIG.17 will be described as an example for the purpose of ease andconvenience in explanation. However, the following manufacture processesmay be applied to the structure of FIG. 18.

Referring to FIG. 19, the remaining portion of the sacrificial fillingpattern 114 may be removed to form recess regions RS. In someembodiments, removing the remaining portion of the sacrificial fillingpattern 114 may be performed using an isotropic etching process thatselectively removes the sacrificial filling pattern 114. For example, ifthe active pattern AP includes silicon (Si) and the sacrificial fillingpattern 114 includes silicon-germanium (SiGe), the isotropic etchingprocess may be performed using an etchant including peracetic acid(C₂H₄O₃) and hydrofluoric acid (HF). In this case, a ratio of an etchrate of the sacrificial filling pattern 114 to an etch rate of activepattern AP may be in a range of, for example, about 10:1 to about 100:1.The etch rates may be changed according to a germanium content of thesacrificial filling pattern 114. The remaining portion of thesacrificial filling pattern 114 may be selectively and easily removed bythe isotropic etching process. In other words, the sacrificial fillingpattern 114 disposed under the second gate spacer SP2 may be easilyremoved by the isotropic etching process. A shape of the recess regionRS may be the substantially same as that of the second preliminaryrecess region 117. In other words, each of the recess regions RS mayhave first sidewalls Si substantially perpendicular to the top surfaceof the substrate 100, second sidewalls S2 slanted with respect to thetop surface of the substrate 100, and a bottom surface BS substantiallyparallel to the top surface of the substrate 100. The second sidewallsS2 may be very short or may not be formed. Thus, the recess region RSmay have a cross section having a rectangular shape or a shape similarto a rectangular shape. The bottom surfaces BS of the recess regions RSmay be disposed at the substantially same level as the top surfaces (orthe topmost ends) of the device isolation patterns 102. The recessregions RS may include undercut regions 120 disposed under the secondgate spacers SP2. A shape of the undercut region 120 may be thesubstantially same as the shape of the second portion 124 of thesource/drain region SD described with reference to FIG. 12B.

Referring to FIG. 20, source/drain regions SD may be formed on innersurfaces of the recess regions RS, respectively. A material and a methodof forming the source/drain regions SD may be the same as or similar tothose described with reference to FIGS. 10A and 10B. The source/drainregions may be formed by performing a SEG process using the activepattern AP exposed through the recess regions RS as a seed. Each of thesource/drain regions SD may fully fill each of the recess regions RS. Inaddition, the source/drain regions SD may protrude from the top surfacesof the active fins AF. The shapes of the source/drain regions SD may besimilar to those described with reference to FIGS. 12A and 12B.

Referring to FIG. 21, a lower interlayer insulating layer 130 may beformed on the substrate 100 having the source/drain regions SD. Next,the gate mask pattern 109, the sacrificial gate pattern 107 and the etchstop pattern 105 may be removed to form a gap region 140 between thegate spacers GSP. A method of forming the lower interlayer insulatinglayer 130 and the gap region 140 may be the same as or similar to themethod described with reference to FIGS. 11A and 11B.

Referring again to FIGS. 12A and 12B, a gate dielectric pattern GD and agate electrode GE may be formed to fill the gap region 140. The gatedielectric pattern GD may extend along a bottom surface of the gateelectrode GE and may also extend onto both sidewalls of the gateelectrode GE so as to be disposed between the gate electrode GE and thegate spacers GSP. Next, an upper portion of the gate electrode GE may berecessed, and a gate capping pattern GP may be disposed on the recessedgate electrode GE. Materials and methods of forming the gate dielectricpattern GD, the gate electrode GE and the gate capping pattern GP may bethe same as or similar to those described with reference to FIGS. 1A and1B.

FIG. 22 is a circuit diagram of a complementarymetal-oxide-semiconductor static random access memory cell (CMOS SRAMcell) including a field effect transistor according to exampleembodiments of the inventive concepts. Referring to FIG. 22, a CMOS SRAMcell may include a pair of driver transistors TD1 and TD2, a pair oftransfer transistors TT1 and TT2, and a pair of load transistors TL1 andTL2. The driver transistors TD1 and TD2 may correspond to pull-downtransistors, the transfer transistors TT1 and TT2 may correspond to passtransistors, and the load transistors TL1 and TL2 may correspond topull-up transistors. The driver transistors TD1 and TD2 and the transfertransistors TT1 and TT2 may be NMOS transistors, and the loadtransistors TL1 and TL2 may be PMOS transistors. At least one of thedriver transistors TD1 and TD2, the transfer transistors TT1 and TT2 andthe driver transistors TL1 and TL2 may be a semiconductor deviceaccording to some embodiments of the inventive concepts.

The first driver transistor TD1 and the first transfer transistor TT1may be in series to each other. A source region of the first drivertransistor TD1 may be electrically connected to a ground line Vss, and adrain region of the first transfer transistor TT1 may be electricallyconnected to a first bit line BL1. The second driver transistor TD2 andthe second transfer transistor TT2 may be in series to each other. Asource region of the second driver transistor TD2 may be electricallyconnected to the ground line Vss, and a drain region of the secondtransfer transistor TT2 may be electrically connected to a second bitline BL2.

A source region and a drain region of the first load transistor TL1 maybe electrically connected to a power line Vcc and a drain region of thefirst driver transistor TD1, respectively. A source region and a drainregion of the second load transistor TL2 may be electrically connectedto the power line Vcc and a drain region of the second driver transistorTD2, respectively. The drain region of the first load transistor TL1,the drain region of the first driver transistor TD1, and a source regionof the first transfer transistor TT1 may correspond to a first node N1.The drain region of the second load transistor TL2, the drain region ofthe second driver transistor TD2, and a source region of the secondtransfer transistor TT2 may correspond to a second node N2. A gateelectrode of the first driver transistor TD1 and a gate electrode of thefirst load transistor TL1 may be electrically connected to the secondnode N2. A gate electrode of the second driver transistor TD2 and a gateelectrode of the second load transistor TL2 may be electricallyconnected to the first node N1. Gate electrodes of the first and secondtransfer transistors TT1 and TT2 may be electrically connected to a wordline WL. The first driver transistor TD1, the first transfer transistorTT1, and the first load transistor TL1 may constitute a first half-cellH1. The second driver transistor TD2, the second transfer transistorTT2, and the second load transistor TL2 may constitute a secondhalf-cell H2.

FIG. 23 is a block diagram illustrating an electronic system including asemiconductor device according to some embodiments of the inventiveconcepts.

Referring to FIG. 23, an electronic system 1100 according to someembodiments of the inventive concepts may include a controller 1110, aninput/output (I/O) unit 1120, a memory device 1130, an interface unit1140, and a data bus 1150. At least two of the controller 1110, the I/Ounit 1120, the memory device 1130 and the interface unit 1140 maycommunicate with each other through the data bus 1150. The data bus 1150may correspond to a path through which electrical signals aretransmitted.

The controller 1110 may include at least one of a microprocessor, adigital signal processor, a microcontroller, or other logic deviceshaving a similar function to any one thereof. The I/O unit 1120 mayinclude a keypad, a keyboard and/or a display device. The memory device1130 may store data and/or commands. The interface unit 1140 maytransmit electrical data to a communication network or may receiveelectrical data from a communication network. The interface unit 1140may operate by wireless or cable. For example, the interface unit 1140may include an antenna or a wireless/cable transceiver. Although notshown in the drawings, the electronic system 1100 may further include afast dynamic random access memory (DRAM) device and/or a fast SRAMdevice as a cache memory for improving an operation of the controller1110. Semiconductor devices according to some embodiments of theinventive concepts may be provided in the memory device 1130, thecontroller 1110 and/or the I/O 1120.

The electronic system 1100 may be applied to a personal digitalassistant (PDA), a portable computer, a web tablet, a wireless phone, amobile phone, a digital music player, a memory card, or other electronicproducts receiving or transmitting information data by wireless.

FIG. 24 is a block diagram illustrating an electronic device including asemiconductor device according to some embodiments of the inventiveconcepts.

Referring to FIG. 24, an electronic device 1200 may include asemiconductor chip 1210. The semiconductor chip 1210 may include aprocessor 1211, an embedded memory 1213, and a cache memory 1215.

The processor 1211 may include one or more processor cores C1 to Cn. Theone or more process cores C1 to Cn may process electrical data and/orelectrical signals. The process cores C1 to Cn may include semiconductordevices according to some embodiments of the inventive concepts.

The electronic device 1200 may perform a specific function correspondingto the processed data and signals. For example, the processor 1211 maybe an application processor.

The embedded memory 1213 may exchange first data DAT1 with the processor1211. The first data DAT1 may be data processed or to be processed bythe one or more processor cores C1 to Cn. The embedded memory 1213 maymanage the first data DAT1. For example, the embedded memory 1213 maybuffer the first data DAT1. In other words, the embedded memory 1213 mayact as a buffer memory or working memory of the processor 1211.

In some embodiments, the electronic device 1200 may be applied to awearable electronic device. The wearable electronic device may mainlyperform a function requiring a relatively small quantity of operations.Thus, if the electronic device 1200 is applied to the wearableelectronic device, the embedded memory 1213 may not need a great buffercapacity.

The embedded memory 1213 may be a SRAM. An operating speed of the SRAMmay be faster than that of a DRAM. When the SRAM is embedded in thesemiconductor chip 1210, it is possible to realize the electronic device1200 having a small size and a fast operating speed. In addition, whenthe SRAM is embedded in the semiconductor chip 1210, consumption of anactive power of the electronic device 1200 may be reduced. The SRAM mayinclude a semiconductor device according to some embodiments of theinventive concepts.

The cache memory 1215 may be mounted on the semiconductor chip 1210along with the one or more process cores C1 to Cn. The cache memory 1215may store cache data DATc. The cache data DATc may be data used by theone or more process cores C1 to Cn. The cache memory 1215 may have arelatively small capacity but may have a very fast operating speed. Insome embodiments, the cache memory 1215 may include a SRAM including asemiconductor device according to some embodiments of the inventiveconcepts. When the cache memory 1215 is used, it is possible to reducean accessing number and an accessing time of the processor 1211 withrespect to the embedded memory 1213. Thus, the operating speed of theelectronic device 1200 may be improved when the cache memory 1215 isused.

In FIG. 24, the cache memory 1215 is separated from the processor 1211for the purpose of ease and convenience in explanation. However, in someembodiments, the cache memory 1215 may be included in the processor1211. In other words, the inventive concepts are not limited to theembodiment illustrated in FIG. 24.

The processor 1211, the embedded memory 1213, and the cache memory 1215may transmit electrical data on the basis of at least one of variousinterface protocols. For example, the processor 1211, the embeddedmemory 1213, and the cache memory 1215 may transmit electrical data onthe basis of at least one interface protocol of universal serial bus(USB), small computer system interface (SCSI), peripheral componentinterconnect (PCI) express, advanced technology attachment (ATA),parallel ATA (PATA), serial ATA (SATA), serial attached SCSI (SAS),integrated drive electronics (IDE), or universal flash storage (UFS).

The electronic system 1100 of FIG. 23 may be applied to electroniccontrol devices of various electronic products. FIG. 25 illustrates amobile phone 2000 implemented with the electronic system 1100 of FIG.23. The electronic system 1100 of FIG. 23 may also be applied to aportable notebook, a MP3 player, a navigation device, a solid state disk(SSD), cars, or household appliances.

According to some embodiments of the inventive concepts, the recessregions may be formed in the active pattern at both sides of thesacrificial gate pattern including the gate spacer, and then thesource/drain regions may be formed to fill the recess regions. A portionof the active pattern under the gate spacer may be replaced with thesacrificial filling pattern of which the etch rate is higher than thatof the active pattern, and thus, the sacrificial filling patterndisposed under the gate spacer may be easily removed during the etchingprocess for forming the recess regions. As a result, the recess regionmay be formed to have the U-shaped cross-sectional profile of which theboth end portions are substantially perpendicular to the top surface ofthe substrate. This means that the uniform junction profile may berealized between the active pattern (i.e., the active fin) disposedunder the gate electrode and the source/drain region filling the recessregion. Thus, the electrical characteristics of the semiconductor devicemay be improved.

While the inventive concepts have been described with reference toexample embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the spirits and scopes of the inventive concepts. Therefore, itshould be understood that the above embodiments are not limiting, butillustrative. Thus, the scopes of the inventive concepts are to bedetermined by the broadest permissible interpretation of the followingclaims and their equivalents, and shall not be restricted or limited bythe foregoing description.

What is claimed is:
 1. A method of forming an integrated circuit devicecomprising: forming a gate structure on a substrate; forming a firstetch mask on a sidewall of the gate structure; anisotropically etchingthe substrate using the gate structure and the first etch mask as anetch mask to form a preliminary recess in the substrate; forming asacrificial layer in the preliminary recess; forming a second etch maskon the first etch mask, the first etch mask extending between thesidewall of the gate structure and the second etch mask; etching thesacrificial layer and the substrate beneath the sacrificial layer usingthe gate structure and the first and second etch masks as an etch maskto form a source/drain recess in the substrate, a sidewall of thesource/drain recess being recessed toward the gate structure relative toan outer surface of the second etch mask; and forming a source/drain inthe source/drain recess.
 2. The method of claim 1, wherein etching thesacrificial layer and the substrate comprises exposing a sidewall of thepreliminary recess that comprises the sidewall of the source/drainrecess.
 3. The method of claim 2, wherein forming the first etch maskcomprises forming the first etch mask having a thickness of about 1 nmto about 10 nm on the sidewall of the gate structure such that asidewall of the preliminary recess is spaced apart from the sidewall ofthe gate structure by about 1 nm to about 10 nm.
 4. The method claim 1,wherein an upper portion of a sidewall of the preliminary recess issubstantially perpendicular to a lowermost surface of the gatestructure.
 5. The method claim 1, wherein the preliminary recesscomprises a first preliminary recess, and wherein etching thesacrificial layer and the substrate comprises: etching the sacrificiallayer and the substrate using the gate structure and the first andsecond etch masks as an etch mask to form a second preliminary recess inthe sacrificial layer and the substrate; and removing the sacrificiallayer to form the source/drain recess in the substrate.
 6. The method ofclaim 5, wherein the second preliminary recess extends through thesacrificial layer.
 7. The method of claim 1, wherein etching thesacrificial layer and the substrate comprises performing an anisotropicetch process and an isotropic etch process.
 8. The method of claim 7,wherein etching the sacrificial layer and the substrate comprisesetching the sacrificial layer faster than the substrate.
 9. A method offorming an integrated circuit device comprising: forming a gatestructure on a substrate; forming a sacrificial layer adjacent asidewall of the gate structure in the substrate, an upper portion of asidewall of the sacrificial layer being substantially perpendicular to alowermost surface of the gate structure; forming an etch mask on thesidewall of the gate structure and a portion of the sacrificial layer;etching the sacrificial layer and the substrate beneath the sacrificiallayer using the gate structure and the etch mask as an etch mask to forma source/drain recess in the substrate; and forming a source/drain inthe source/drain recess.
 10. The method claim 9, wherein an uppermostsidewall of the source/drain is recessed toward the gate structurerelative to an outer surface of the etch mask.
 11. The method claim 10,wherein the uppermost sidewall of the source/drain is substantiallyperpendicular to the lowermost surface of the gate structure.
 12. Themethod claim 9, wherein etching the sacrificial layer and the substratecomprises: etching the sacrificial layer and the substrate using thegate structure and the etch mask as an etch mask to form a preliminaryrecess that extends through the sacrificial layer; and removing thesacrificial layer to form the source/drain recess in the substrate. 13.The method claim 12, wherein removing the sacrificial layer comprisesexposing a sidewall of the preliminary recess such that the sidewall ofthe preliminary recess comprises a sidewall of the source/drain recess.14. The method of claim 9, wherein forming the sacrificial layercomprises: etching the substrate to form a recess adjacent the sidewallof the gate structure in the substrate, the sidewall of the recess beingsubstantially perpendicular to the lowermost surface of the gatestructure; and performing an epitaxial growth process using a surface ofthe recess as a seed layer to form the sacrificial layer in the recess.15. A method of forming an integrated circuit device comprising: forminga gate structure on a substrate; forming a first recess adjacent asidewall of the gate structure in the substrate, a sidewall of the firstrecess being substantially perpendicular to a lowermost surface of thegate structure and being spaced apart from the sidewall of the gatestructure by a first distance; forming a sacrificial layer in the firstrecess; forming a second recess that extends through the sacrificiallayer and in a portion of the substrate beneath the sacrificial layer,an uppermost sidewall of the second recess being spaced apart from thesidewall of the gate structure by a second distance that is greater thanthe first distance; removing the sacrificial layer to form asource/drain recess in the substrate; and forming a source/drain in thesource/drain recess.
 16. The method of claim 15, wherein the secondrecess has a depth greater than a depth of the first recess.
 17. Themethod of claim 15, wherein removing the sacrificial layer comprisesexposing the sidewall of the first recess such that the sidewall of thefirst recess comprises a sidewall of the source/drain recess.
 18. Themethod of claim 17, wherein the first distance is about 1 nm to about 10nm.
 19. The method of claim 15, wherein the uppermost sidewall of thesecond recess exposes the sacrificial layer.
 20. The method of claim 15,wherein an uppermost sidewall of the source/drain is spaced apart fromthe sidewall of the gate structure by a third distance that is smallerthan the second distance.